Press bed drive



Sept 1949- J. c. E. BOURASSA 2,483,121

' PRESS BED DRIVE 7 Filed May 3, 1946 IV, I @f Patented Sept. 27, 1949 PRESS BED DRIVE Joseph Cyrille Emile Bourassa, Montreal, Quebec,

Canad Application May 3, 1946, Serial No. 667,040

In Canada May 26, 1945 2 Claims. (01. 74-58) The present invention relates to printing presses and, more particularly, to the driving means of such presses having a reciprocating bed and a cylinder.

Various means are presently used for actuating the bed of printing presses, among which may be mentioned the double-thread shaft arrangement such as, for instance, the one disclosed in United States Patent No. 1,543,493, dated June 23, 1925.

Briefly described, the disclosure of this patent comprises, essentially, a rotating shaft held against longitudinal displacement and mounted axially in parallel relation tothe axis of the reciprocating bed. Said shaft has threads thereon, which are crossed in opposite directions and in which a shoe is movable. This shoe is attached to the bed and, accordingly, entrains the said bed therewith as it moves along the shaft when same is rotated. Inasmuch as the threads run in reverse directions the shoe, consequently, will be transferred from one to the other, at the ends thereof, and impart to the bed a reciprocating movement.

This bed motion is well adapted to small presses, especially of the type shown in the patent above referred to, wherein a carriage for the inking rollers is caused to travel across the bed by the simple expedient of using a second shoe on the same screw, opposite the first one. On large presses, however, the operating stresses encountered require a much larger shoe and consequent enlargement of the physical size of thread and. screw, the result is a wide gap where the threads cross, which gaps present sharp edges subject to wearing and consequent looseness of the moving elements showing up as faulty printing.

The present invention has been conceived to avoid the drawbacks enumerated above and has for its main object the provision of highly improved and efficient means for driving the bed of printing presses by means of crossed-thread screws.

Another object concerns printing press beddriving means adaptable to large, heavy, presses, economically and easily.

A further object envisages means of the character described whereby a printing press bed can be actuated by a pair of crossed-thread twin screws in a simple and relatively inexpensive manner.

Other objects and advantages of the invention will become apparent, or be pointed out further, during the description to follow.

As an example, and, for purposes of illustration, an embodiment of the invention is shown inthe annexed drawing, wherein:

Figure 1 is a somewhat schematic plan View of the drive according to the invention, taken below the bed,

Figure 2 is a partial side representation of a gear and pinion train for rotating the twin screws shown in Figure 1,

Figure 3 is a vertical section taken through the drive and showing the position of the swing-bar at the point of reversal of the bed,

Figure 4 is a plan view of the swing-bar showing its angular relation with respect to the screws and bed-plate, shown in dotted lines, during constant speed operation thereof, and

Figure 5 is a sectional view, taken on line 5-5 of Fig. 4.

Referring to the drawing, wherein similar reference characters represent corresponding parts throughout, it will be seen thatlthe drivingmechanism of the invention comprises a pair of twin, parallel, lead screws l0 suitably journalled against longitudinal displacement in a press frame F. Said screws consist of shafts in which helicoidal channels I I and I2 are formed to cross each other at regular intervals in staggered diametrally opposed positions. In other words, the channels constituting screw threads of a suitable pitch are disposed in opposite directions and merge together at point I3 at each end of the screws.

The twin screws are rotated in unison, and in the same rotational direction, by means of pinions l5 keyed to the outer ends thereof and meshing with a gear l6 suitably driven.

Shoes 20 engage the channels of the screws, as shown in Figures 1 and 3, said shoes consisting of a flat memberprovided with a concave depression adapted to fit snugly around the reduced diameter of the screw (Fig. 3). The said shoes are provided with a shank 2| freely mounted in the center bore 22 of a sliding block 23.

This block is splined to move longitudinally within the arms 25 of a swing-bar indicated generally at B. Said swing-bar is pivoted centrally around a stub shaft or pin 26, integral with a plate 21 adapted to connect said bed 30 with the swing bar B. Thus, the swing-bar is pivoted to the bed, and the shoes, in turn, are pivoted to sliding blocks movable in the bar.

The mechanism being assembled as shown in Figure 1, it will be evident that the shoe at each end of the bar being engaged with the correct thread, the bar will be moved longitudinally when the gear It causes the screws to revolve in unison.

Inasmuch as one end of the bar is shifted longitudinally a distance corresponding to the pitch of one thread, the bar will be normally inclined with respect to the axis of the screws. Since both ends of the bar are entrained at equal speed, said bar will, in turn, cause longitudinal movement of the bed through the intermediary of the pin 26 g This particularconstruction presents distinct advantages over the single-screw drive for presses:

1. The swing-bar and shoes being locatedflnearer the bed than in any other driving mechanism, more easily controlled acceleration.andretamdae tion of the bed may be had which can be converted into higher speeds. the said driving mechanisms frees the under side of the press, whereby easier access thereto is possible, a distinct advantage in presses mounted di rectly on a floor having no pit.

One end f thei'swingdiarbeingireversed' before the: otlier,thefmovement of the bed is gradually diminished to a stan'd still. before being reversed;

3; The-drivingshoes being-'at'theendof a lever constituted by the arms 25, the amplitudeof any looseness in said Eshoes= is reduced in two before being transmitted to the bed. Consequently; the bridging of the crossed-threads gaps has little eficton' the bed motion e'spe'cially-when', as shown inFigur'e 1, the screws 1 are timedtogether so that one shoe bridges a-gap while the other is disposed between gaps;

41 Compared with conventional reversing mechanisms, the present arrangement isa structural simplificationresulting in-a' greatsaving in weight an -space. V

5, Due to the sliding action of the shoes, the o era icn'i er s e i The drivi e ementbe n com ise of two smalllateral screws, insteadlof a large central one the bed can belowered i e avin i 'heie s ad, or b t era es bi itv obta ned'u er he presses mentioned under 1;

The compactness of '7. The actuating members are easily accessible and adapted to be changed rapidly and at low cost.

From the foregoing, it should be apparent that the present invention is an advance in the art of driving the bed of printing presses, especially large ones.

Itnmst be understood: also, ttiativa-rious changes as tothe size, shape and-arrangement-of parts may be resorted to without departing from the spirit of the invention or the scope of the appended'c-laims.

Having thus described my invention, I claim:

1'. As driving m'eans for the bed of a printing press, a pair of spaced parallel cross-thread sorews means for synchronously rotating said screws, shoes engaged in the threads of the screws, a swing-bar centrally pivoted to the bed of a press;- and means for slidably supporting the shoes in the ends of theiswing bar.

-2;,l\/leans causing, a reciprocatory longitudinal movement-having I gradually retardegland accelerated-gradients,- comprising a pair of Spaced parallel members reciprocated longitudinally by means of synchronized crossed-thread screws, a swing bar joining together said membersv ,angua larlywwith respect tothe longitudinalaxisofthe screws,- and means disposed. centrally of the swing bar for: pivoting thereto an element tube moved.

JOSEPHCYRILLE EMILE .BOURASSA;

REFERENCES CITED The following references-:areoi record in the file of J this patent? UNITED STATES PA'I'ENTSJ Number Name Date:

661,693 Hazelhurst Nov. 13; 1999 1,734,649 Shull Nov. 5,1929: 2,-30'1975 Walter Milan; 12,1943- 25324-3329 Sh'afiner J uly 13; 1943, 

